Susan Jebb, a government adviser on obesity, recommends swapping fruit juice for a piece of real fruit, and says fruit juice should be diluted. Photograph: Getty Images

An adviser to the government on obesity has called for fruit juice to be removed from the recommended list of five-a-day portions of fruit or vegetables, saying it contains as much sugar as many soft drinks.

Jebb told the Sunday Times she did not see juice as a healthy option: "I would support taking it out of the five-a-day guidance," she said. "Fruit juice isn't the same as intact fruit and it has got as much sugar as many classical sugar drinks. It is also absorbed very fast so by the time it gets to your stomach your body doesn't know whether it's Coca-Cola or orange juice, frankly.

"I have to say it is a relatively easy thing to give up. Swap it and have a piece of real fruit. If you are going to drink it, you should dilute it."

Popkin, a professor of nutrition at the University of North Carolina, told the Guardian that fruit juices and fruit smoothies were "the new danger".

He said: "Think of eating one orange or two and getting filled. Now think of drinking a smoothie with six oranges and two hours later it does not affect how much you eat. The entire literature shows that we feel full from drinking beverages like smoothies but it does not affect our overall food intake, whereas eating an orange does. So pulped-up smoothies do nothing good for us but do give us the same amount of sugar as four to six oranges or a large coke. It is deceiving."

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